Foxes

Foxes typically hunt at dusk or dawn, although they may attack during the day if impelled by hunger or to satisfy their young. They can become quite bold in more populated areas, as well. Once foxes discover easy pickings, they may decimate a flock through nightly visits. At the same time, foxes are smart, with an acute sense of smell, and will quickly detect any traps or modifications you have made to thwart them. Although they will grab free-range chickens, foxes are one of the few animals patient enough to dig their way into poultry housing. They usually carry away their prey to eat in a safe location. However, if they are baffled in their attempts to dig, they may just grab the nearest leg, much like a raccoon.
If a fox has visited your flock, you may not see much evidence other than the fact that a chicken is missing. There may be a pile of feathers at the site of the kill, and there may also be a trail of feathers leading away. If you happen to find the place where the fox ate its prey, you might see mangled feathers, some plucked and others bitten off. If you see the body, it will likely have a broken neck.
Like most predators, foxes will not challenge properly maintained electric poultry netting. Livestock guardian dogs can also be highly effective in keeping foxes away. In more urban areas where guard dogs or electric netting are not options, motion-activated spotlights or sprinklers can be an effective deterrent. Another key to keeping foxes away from chickens is to remove brush and other cover where these predators can hide to plot an attack.
Coyotes
Coyotes are typically only a threat to free-ranging flocks, although they may bowl over weak fencing. They are becoming increasingly bold in invading urban areas, and are also not shy about hunting in the daytime. Coyotes take only what they intend to eat that day.
As with bobcats, coyotes leave very little trace. You may only notice that a chicken is missing. At most, you may see a trail of feathers. However, if a chicken disappeared from a pen, and the fence has been physically knocked down, you are probably dealing with a coyote, not a bobcat. In rare cases, you might find a skeleton surrounded by randomly scattered clumps of feathers stuck together with saliva and having the tips of the quills cleanly sheared off by the coyote’s powerful back molars. The neck may be broken.
Deterring coyotes is not terribly complicated. Keep your chickens safely enclosed within electric poultry netting, and leave the fence on day and night.
Domestic Dogs
Domestic dogs can be a severe problem for those who keep chickens in populated areas. They are among the predators most likely to attack during the day. Chicken-killing dogs almost invariably hunt for fun rather than food, and as soon as one bird is dispatched the dog will immediately take off in pursuit of another. Dogs can wipe out an entire flock in a short amount of time.
A telltale sign of a dog attack is a general appearance of chaos and confusion, with multiple dead chickens scattered over a wide area, being mutilated rather than eaten. Chickens may have been pulled through fencing, or fencing and housing may have been partially demolished. A few chickens may be missing altogether. Survivors may show signs of injury.
Electric poultry netting is effective for deterring dogs, as is a reliable livestock guardian dog. In an urban setting, keeping your chickens housed in a secure coop and run may be your only option. As for training your own dog, a controlled introduction is often sufficient, as most dogs can and will learn to respect their master’s property. Should you have a dog that you are not entirely sure about, a fenced yard for the dog and an electrified pen for the chickens will keep them separate.